1. Field of the Invention
The present invention relates to those refrigeration systems specially designed for the refrigeration of foods. In a more particular sense the invention relates to systems of this type installed in food supermarkets, and typically incorporating a multiplicity of evaporators cooled by refrigerant flowing in a closed circuit that includes, additionally, a remotely mounted condenser and a series of compressors mounted in parallel.
The invention, in a more specific sense, may be regarded as an improvement in a refrigeration system of the described type in which power savings are effected through subcooling and to perhaps even a greater extent, through lowered head pressures.
In yet a more particular sense, the improvement can be appropriately classified as an automatic control in a refrigeration system of the described type, adapted to cause pressures within a surge receiver to closely follow those of the liquid line as sensed at a location between the condenser and an inlet pressure regulating valve mounted in the liquid line downstream from the condenser.
2. Description of the Prior Art
Refrigeration systems in which the present invention is especially adapted to be incorporated, are disclosed in U.S. Pat. Nos. 3,905,202 to Taft et al; 4,012,921 to Willitts et al; and 4,231,229 also to Willitts.
In U.S. Pat. No. 4,231,229 there is disclosed a refrigerating system in which a receiver pressure control valve is of the differential pressure regulating type, and is sensitive to a difference in pressures between the compressor discharge line and the liquid line. The valve, in these circumstances, operated to communicate the receiver with the compressor discharge line to automatically adjust the receiver pressure to a value that is a function of the pressure differential between the compressor discharge line and the liquid line.
While this arrangement has worked with full efficiency, in most instances, it has been found that in some situations the valve arrangement does not function with full accuracy.
This, it is believed, is due very possibly to the fact that in every installation of a refrigeration system in a supermarket, the specific length and size of the piping used, the location of the condenser, the location and number of the compressors, the environmental conditions, humidity, and the number and location of the refrigerated cases, will differ from other installations. As a result, it is sometimes found that a valve arrangement such as found in U.S. Pat. No. 4,239,229 will operate with full efficiency in the great majority of installations, but will be affected adversely by one or more of the listed factors in the remaining installations in which use of the patented system disclosed in U.S. Pat. No. 4,231,229 is sought.
The present invention has as its main object the provision of a valve arrangement that will be usable to advantage in a fully efficient way, in those situations in which the peculiarities of a particular installation have prevented the arrangement of U.S. Pat. No. 4,231,229 from operating with maximum efficiency.